<script src="./vue.js"></script>

<body>
    <div id="app">
        <div v-bind:id="datd | formatld"></div>
    </div>
</body>
<script>
    var vue = new Vue({
        el: '#app',
        data: {
            datd: 'dff1',
        },
        filters: {
            formatld(value) {
                console.log(value.charAt(1))
                console.log(value.indexOf("d"))
                return value ? value.charAt(1) + value.indexOf('d') : '';
            }
        }
    });
</script>